No, but dual-boot with the existing OS as the default is a simple workaround. Here's how.
– Tom BrossmanMay 30 '12 at 20:27

2

Assuming this is a Windows system with multiple users, dual-boot will affect other users because they have to boot Windows each time (instead of just logout/login) and the bootloader will change (even if Wubi is used).
– ishMay 30 '12 at 23:25

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Please take a moment to come back, GoonerJoe97 and accept the answer you feel was the best (check mark on the left). This marks the question as closed so that future readers can benefit from it.
– ishJun 16 '12 at 6:17

4 Answers
4

No, you cannot install Ubuntu without affecting the ENTIRE computer, and therefore all users using it.

Why?

Let me explain: whether you install Ubuntu from Windows (Wubi), or alongside Windows by booting from an Ubuntu Live-CD, Ubuntu will make three changes that will affect the entire computer and all its users:

It will change the way the computer starts up (in technical terms, modify the bootloader)

It will occupy a significant amount of hard disk space (at least 4 gigabytes or so.)

While Ubuntu is running, the other users cannot login to Windows (because it cannot run at the same time as Ubuntu).

Minimally-invasive installation: run in a virtual machine

I assume you are using Windows. If you have administrative rights, you can try installing Ubuntu in a virtual machine using VirtualBox or VMWare Player. Both are free. But this can also affect users in two ways:

Running a virtual machine will also use a significant amount of RAM (at least 1024 MB recommended) and some CPU (processor) time, which can affect the responsiveness of the system for other users using it without you logging out.

The only way to do what you are asking would be to run Ubuntu in a virtual machine.

To do this
1, Download Ubuntu, and a VM tool like Virtual Box Link Here
2, Install Ubuntu saving the VDI file to a user specific directory (like your home folder). As long as other users don't have access to your home folder, they won't be able to run your Virtual Ubuntu machine.

Ubuntu is an operating system that runs your computer. This is different from an application where you can choose per user what programs will run or not. So once your computer boots into Ubuntu the whole machine will run on Ubuntu.

If you only want to try out Ubuntu you could install it in a Virtual Machine that will run like an application on a per user basis. But this will be at the cost of performance for Ubuntu of course.

What you can do if only you but not other users want to run on Ubuntu is to set up a dual boot with your primary OS. This can be configured in a way that your primary OS will be booted per default. Only if somebody, i.e you, wants to boot Ubuntu you will have to press a key during boot-up to select a different OS (Ubuntu in this case).

So my answer is yes, you can install Ubuntu for yourself and have the alternative OS for other users (almost) unchanged.

You should however ask the other user if that is o.k. with them, and you definitely have to back up the whole system before you install Ubuntu to be able to restore the previous settings in case something goes wrong. Installing a dual boot Ubuntu involves changes to the harddisk partition which is a potential risk to the data on it. You may also want to think about a separate hard drive just for Ubuntu to not put the data of the other users at risk.

Another fact you might want to know is that Ubuntu replaces a bootloader by it's own (Grub). Therefore when removing Ubuntu we also need to resotore the original bootloader. For e.g. Windows you will need an installation or a repair CD to do so.